[run] gdsh run is working

Added more stdio helpers, added justification for hostnames. Added interim output support.

al@zorak.tobert.org ~/src/gdsh $ go build && ./gdsh run -c uptime
Connection pool is up!
Waiting for all tasks to run ...
        localhost:  04:12:08 up 8 days, 30 min,  9 users,  load average: 0.17, 0.21, 0.18
               z2:  04:12:08 up 8 days, 30 min,  9 users,  load average: 0.17, 0.21, 0.18
 zorak.tobert.org:  04:12:08 up 8 days, 30 min,  9 users,  load average: 0.17, 0.21, 0.18
               z3:  04:12:08 up 8 days, 30 min,  9 users,  load average: 0.17, 0.21, 0.18
               z1:  04:12:08 up 8 days, 30 min,  9 users,  load average: 0.17, 0.21, 0.18